ADHERENCE OF CHEWING GUM TO DENTAL RESTORATIVE MATERIALS

Purpose: To describe a method whereby chewing gum tackiness can be mea sured. Materials and Methods: The chewing gum used for the experiment was V6(2) (Freshmint). Paladur denture base material, Silux Plus, P-50 and Heliomolar resin composites and Luxalloy amalgam were used. Squar ed specimens (15x15x2 mm) composed of the polymerized materials tested or set amalgam were made with a mold. As gold specimen, a gold-plated brass specimen was used, having the same dimension as specified above . A tooth enamel specimen (5 x 5 mm) was made out of flat ground human enamel from an incisor. All specimens were stored for more than 7 day s in water before use, and wet ground on paper No. 320 immediately bef ore testing. The adhesion was measured by a balance equipped with a re corder and a bottom attachment, to which a chain was mounted. The end of the chain was attached to a quadratic brass plate, to which one of the above described specimen was glued by cyanoacrylate. Another brass plate, with an attached specimen of the same material, was mounted in a small vice in such way that the two specimens were parallel with an d facing each other. A motor drive enabled parallel removal of the two plates from each other. The gum was chewed approximately 1 second bet ween bites and for various periods of time. It was then pressed betwee n the two parallel squares (mentioned above) of restorative materials or enamel, reaching a final distance of 1 mm between the plates and oc cupying the entire space between the plates. The study was carried out at 36 degrees C, and the two plates were wetted with fresh saliva or water immediately before placement of the chewing gum. Excess liquid w as removed after the wetting, leaving a thin film. The maximal force d uring parallel removal of the two plates from each other was recorded. The measurements were performed eight times in each group, and the me an adhesion per surface area and SD was expressed as mN/mm(2). The mea surements were repeated for some of the groups. The significance of di fferences between each group was tested by Newman-Keul's Multiple Rang e Test at a 5% level of significance. Results: Adherence of chewing gu m to dental restorative materials and enamel was found to decrease as follows: denture base material > resin composites = silver amalgam > g old > human enamel. The adhesion was dependent on gum base and not on the sweetening additives and reached a maximum after about 2 minutes' chewing.